JP4509876B2 - Optical filter - Google Patents

Description

  The present invention relates to an optical filter disposed on the viewing side of an image display screen.

For example, it is known to use an image display screen such as a liquid crystal display, a CRT display, a plasma display or the like with an optical filter having light transmittance and functionality corresponding to various purposes.
For example, as an optical filter having a function of preventing peeping on a display screen of a mobile phone, a portable information terminal, etc., in Patent Document 1 below, a plurality of transparent silicone rubber sheets and colored silicone rubber sheets are alternately arranged and integrated. An antiglare layer is formed, a light transmitting layer is provided on the surface of the antiglare layer, and an adhesive layer is provided on the back surface of the antiglare layer. According to the optical filter having such a configuration, it is possible to prevent peeping from the side without impairing the visibility of the display image from the user.
JP 2003-131202 A

However, the optical filter of the above example is used by being attached to a display screen of a mobile phone, for example. However, the optical filter merely has a function of preventing peeping from the side, and since there is no pattern, it is visually It is not very interesting as a mobile phone accessory.
In addition, the optical filter arranged on the viewing side of the image display screen is not limited to the above example, and if a pattern is provided, the visibility of the image display screen may be impaired. There were many restrictions such as the area to be applied was limited to the corner.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide an optical filter that can improve the degree of freedom of decoration while ensuring the visibility of a display image. .

In order to achieve the above object, the optical filter of the present invention is an optical filter arranged on the viewing side of the image display screen, and is formed by dot printing in a region overlapping the display image on the image display screen. A light transmittance in a wavelength range of 400 to 1200 nm of only the halftone dot of the printed image is 50% or less, and a dot diameter in the halftone printing is 0.2 mm or less. And the dot area ratio is 60% or less .

  ADVANTAGE OF THE INVENTION According to this invention, the freedom degree of the decoration given to an optical filter can be improved, ensuring the visibility of a display image.

1 and 2 show an embodiment of the optical filter of the present invention. FIG. 1 is a perspective view, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. In the present embodiment, an optical filter having a peeping prevention function will be described as an example. The drawing schematically shows an enlarged part of the optical filter.
The optical filter of this embodiment is schematically configured by forming a print image 2 on one surface of an optical filter main body (hereinafter sometimes simply referred to as a main body) 1.
In the present embodiment, the main body 1 includes an antiglare layer 10 in which light transmission bands 11 and light shielding bands 12 are alternately arranged, and a first transparent protection provided on the entire surface of the antiglare layer 10. It consists of layer 13. The printed image 2 is formed on the surface of the first transparent protective layer 13.
The overall planar shape of the optical filter is, for example, a rectangle, but can be appropriately changed according to the shape of the display screen to be applied.

  The print image 2 is formed by halftone printing. As a halftone printing method, a lithographic (offset) printing method, a waterless lithographic printing method, a resin relief printing method, an intaglio printing method, a screen printing method, an inkjet printing method, a thermal transfer printing method, or the like can be used. . As the waterless lithographic printing method, specifically, a printing method using a lithographic plate in which the non-image area is made of silicone rubber and not using dampening water can be used. Among the printing methods listed above, the waterless flat printing method is preferable from the viewpoint of productivity and expressive power.

When the user views the display screen, even if the display image on the display screen overlaps with the print image 2 on the optical filter disposed on the viewing side of the display screen, favorable visibility of the display image is ensured. Therefore, in dot printing, the dot diameter, which is the size of each dot, is 0.2 mm or less, and the dot area ratio (the ink (halftone dot) of the total area of the printed image 2 exists) It is preferable that the area ratio) is 60% or less. The dot area ratio is more preferably 50% or less.
In order to obtain good visibility of the printed image 2 (picture), the lower limit of the dot diameter is preferably 0.05 mm or more, and more preferably 0.1 mm or more. The lower limit of the dot area ratio is preferably 20% or more, and more preferably 35% or more.
The halftone dot area ratio can be controlled by the dot diameter and / or the number of halftone dots per unit area (resolution).
A preferable resolution range is about 75 to 300 mesh, and more preferably 125 to 250 mesh.

  The material for forming the printed image 2 is not particularly limited, and existing ink suitable for each printing method can be appropriately used. For example, when using a waterless lithographic printing method, general offset printing inks such as an oxidation polymerization type ink, an ultraviolet curable ink, and an evaporation drying type ink can be used. Specific examples of the base material (vehicle) of the ink include acrylate photopolymerizable resins, acrylic resins, vinyl chloride-vinyl acetate copolymer resins, polyester resins, polyurethane resins, and the like.

In the present embodiment, the light transmittance of only the halftone dot (ink layer) is not particularly limited, but is preferably 50% or less and more preferably 20% or less in order to obtain good visibility of the printed image 2 (picture). . There may be 0 (zero)%. The light transmittance of only the halftone dot (ink layer) can be controlled by the composition of the ink and / or the thickness of the ink layer.
In addition, the value of “light transmittance” in the present invention is a value when light transmittance in a wavelength range of 400 to 1200 nm is measured by irradiating C light and D ₆₅ light as a light source.

The shape (design of the pattern) of the printed image 2 is not particularly limited, and can be an arbitrary shape. Further, as for the position where the print image 2 is formed, the decoration is conventionally limited to the corner portion of the display screen. However, in the present embodiment, the print image 2 can be formed at an arbitrary position.
The halftone printing conditions do not have to be uniform throughout the print image 2, and the ink composition, the light transmittance of only the halftone dot (ink) layer, the dot diameter, and the dot area ratio depend on each part of the print image 2. Etc. may be different from each other.

Next, the main body 1 will be described.
When the thickness direction of the main body 1 is the Z direction, and two directions perpendicular to each other in the plane perpendicular to the Z direction are the X direction and the Y direction, respectively, the light transmission band 11 and the light shielding band 12 constituting the antiglare layer 10. Are band-shaped extending in the X direction, and a plurality of light transmission bands 11 and a plurality of light shielding bands 12 are alternately arranged in the Y direction. The widths of the plurality of light transmission bands 11 in the Y direction are uniform and constant in the X direction. The widths of the plurality of light shielding bands 12 in the Y direction are also uniform and constant in the X direction.

  As the material of the light transmission band 11, a highly transparent resin is used. Specifically, a resin having high transparency such that the light transmittance when light is transmitted in the Z direction in the figure with respect to only the light transmission band 11 is 75% or more, preferably 85% or more. Material is preferred. For example, highly transparent thermoplastic resins and thermosetting resins are used. Specific examples include cellulose resins, polyolefin resins, polyester resins, silicone resins, polystyrene resins, polyvinyl chloride resins, acrylic resins, polycarbonates. Examples thereof include resins. Of these, silicone resins are preferred, and silicone rubber is particularly preferred from the viewpoint of heat resistance.

As the material of the light-shielding band 12, a colored resin obtained by using the above-described resin as the material of the light-transmitting band 11 as a base material and adding a colorant such as a pigment or a dye thereto is suitably used. The color tone of the light-shielding band 12 is not particularly limited as long as a preferable light-shielding property in the light-shielding band 12 can be obtained. The color tone of the shading band 12 can be adjusted by the type and amount of the colorant. Specifically, it is preferable that only the light-shielding band 12 has a light-shielding property so that the light transmittance when light is transmitted in the Y direction in the figure is 40% or less, preferably 10% or less. Moreover, since the color tone of the light-shielding band 12 constitutes the color tone recognized when the anti-glare layer 10 (main body 1) is viewed, it is preferable to design in consideration of decorativeness.
Specific examples of the colorant include general organic pigments or inorganic pigments such as carbon black, benkara, iron oxide, titanium oxide, yellow iron oxide, disazo yellow, and phthalocyanine blue. One colorant may be used, or two or more colorants may be used. Moreover, when not using a black pigment, it is preferable to use a white pigment together in order to obtain favorable light-shielding property.
In the antiglare layer 10, the resin material forming the light transmission band 11 and the resin material as the base material of the light shielding band 12 may be the same or different from each other. From the viewpoint of adhesiveness with the band 12, it is preferable that both are the same.

In the antiglare layer 10, the viewing angle θ in a plane perpendicular to the X direction (the paper surface in FIG. 2) is determined by the thickness of the light transmission band 11 in the Z direction and the width in the Y direction. Further, the ratio of the width of the light transmission band 11 to the width of the light shielding band 12 in the Y direction affects the transmittance of light rays parallel to the Z direction.
Specifically, the viewing angle θ in the antiglare layer 10 is preferably in the range of 30 to 150 °, more preferably 60 to 120 °.
The thickness T in the Z direction of the light transmission band 11 is preferably about 0.1 to 2.5 mm, and more preferably about 0.14 to 0.4 mm.
The width W1 in the Y direction of the light transmission band 11 is preferably in the range of 50 μm to 0.3 mm, and more preferably in the range of 75 μm to 0.2 mm.
The width W2 of the light shielding band 12 in the Y direction is preferably in the range of 5 μm to 50 μm, and more preferably in the range of 15 μm to 30 μm.
The thickness T of the light shielding band 12 in the Z direction is the same as the thickness T of the light transmission band 11.

  The antiglare layer 10 having such a configuration can be manufactured as follows. First, a plurality of sheets of the first sheet made of the constituent material of the light transmission band 11 and the thickness W1 and a plurality of sheets of the second sheet made of the constituent material of the light shielding band 12 and the thickness W2 Are alternately laminated, and heated and pressed to form a block body in which the plurality of sheets are integrated. Subsequently, the glare-proof layer 10 is obtained by slicing this block body by a cut surface perpendicular to the sheet surface. The thickness (slice width) when slicing is the above T.

As the material of the first transparent protective layer 13 provided on the surface of the antiglare layer 10, the resins listed above as the material of the light transmission band 11 can be used. The light transmittance when light is transmitted in the Z direction in the figure with respect to the simple substance of the first transparent protective layer 13 is preferably 75% or more, and more preferably 85% or more.
The material of the first transparent protective layer 13 is particularly preferably a polycarbonate, a polyester resin, an acrylic resin, a cycloolefin polymer, or a cellulose film from the viewpoint of transparency and heat resistance, and more preferably a polycarbonate and a polyester resin.
If the thickness of the first transparent protective layer 13 in the Z direction is too thin, a sufficient protective function cannot be obtained, and the light transmittance decreases as the thickness increases, so that the thickness is preferably about 0.01 to 0.5 mm. About 1 to 0.2 mm is more preferable.

A method of providing the first transparent protective layer 13 on the surface of the antiglare layer 10 is not particularly limited, and a known method can be appropriately used.
For example, a method of applying an adhesive on the surface of the antiglare layer 10 and bonding a sheet made of the material of the first transparent protective layer 13 and then curing the adhesive may be used. Thereby, the main body 1 is obtained.
The adhesive used at this time preferably has a high light transmittance after curing. Specifically, it is preferable that the light transmittance of the cured adhesive layer alone is 65% or more, and more preferably 80% or more.
Examples of such an adhesive include a thermosetting adhesive having a transparency after curing, a multi-component reaction adhesive, an ultraviolet curable adhesive, and the like. Specifically, an epoxy adhesive, a urethane adhesive, An acrylic adhesive, a melamine adhesive, a polyester adhesive, a silicone adhesive, and the like can be suitably used.

  The light transmittance of only the main body 1 having such a configuration, that is, the light transmittance of the laminate of the antiglare layer 10 and the first transparent protective layer 13 is preferably 60% or more, and more preferably 70% or more. preferable. The upper limit of the light transmittance is preferably higher, but about 90% is the limit to achieve the peep prevention function.

Moreover, in this embodiment, the adhesion layer 14 which consists of a rubber material which has a light transmittance is provided on the other surface of the main body 1, ie, the back surface of the glare-proof layer 10, as an outermost layer on the opposite side to the printed image 2. Yes. The pressure-sensitive adhesive layer 14 has a mirror-finished surface 14a so that it can be repeatedly attached to and detached from a display screen of a mobile phone or the like.
The adhesive layer 14 having “light transmittance” means that the light transmittance of only the adhesive layer 14 is 85% or more. The preferable range of the light transmittance of the adhesive layer 14 is 90 to 99%, and more preferably 95 to 98%.
As the rubber material constituting the adhesive layer 14, for example, an elastomer (including a gel material of low crosslink density product) can be suitably used. Specific examples include silicone rubber, silicone gel, urethane rubber, urethane gel, and the like. Can be mentioned. Among these, silicone rubber is particularly preferable because it has little adhesive residue when peeled from the display screen and has high light transmittance.

The method of providing the adhesive layer 14 on the back surface of the antiglare layer 10 is not particularly limited, and a known method can be appropriately used.
For example, an adhesion method similar to the method of providing the first transparent protective layer 13 on the surface of the antiglare layer 10 can be used.
When the adhesive layer 14 is provided on the back surface of the main body 1 as in the present embodiment, the light transmittance in the laminate of the adhesive layer 14 and the main body 1, that is, the light transmittance in the region where the printed image 2 is not provided. It is preferably 60% or more, and more preferably 70% or more. The upper limit of the light transmittance is preferably higher, but about 90% is the limit to achieve the peep prevention function.

The optical filter of the present embodiment is used by being pasted on a display screen such as a mobile phone. In the optical filter of this embodiment, since the pattern made of the printed image 2 is formed on the first transparent protective layer 13, the decorative property is imparted and the added value as an accessory is improved.
In addition, since the print image 2 is formed by halftone printing, the visibility of the display image can be ensured even if the print image 2 is formed in an area overlapping the display image, so that the degree of freedom of decoration is high. .
Further, there is an advantage that the print image 2 can be formed by multicolor printing.
Moreover, since the optical filter of this embodiment is equipped with the glare-proof layer 10, it can prevent peeping from a side.

<Modification>
As a modification of the above embodiment, a second transparent protective layer may be provided between the back surface of the antiglare layer 10 and the adhesive layer 14.
The preferred material of the second transparent protective layer, the range of preferred light transmittance, the formation method, and the like can be the same as those of the first transparent protective layer 13.

  In the above-described embodiment, an example in which the print image 2 is provided on an optical filter having a peeping prevention function has been described. However, the present invention is an optical filter that is light transmissive and disposed on the viewing side of the image display screen. The present invention is applicable to any optical filter having various functions as well as a peeping prevention function.

Examples are given below, but the present invention is not limited to these examples.
Example 1
An optical filter having the configuration shown in FIGS.
First, a first sheet made of transparent silicone rubber (trade name: KE153U, manufactured by Shin-Etsu Chemical Co., Ltd.) having a thickness of 200 μm was prepared as the light transmission band 11.
Separately, a second sheet having a thickness of 20 μm made of a material obtained by adding 15 parts by mass of carbon black to 100 parts by mass of transparent silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE153U) as the light shielding band 12. Prepared.
A plurality of first sheets and a plurality of second sheets were alternately laminated, heat vulcanized and pressurized to form a block body in which these sheets were integrated.
Next, the antiglare layer 10 was produced by slicing the block body to a thickness of 360 μm at a cut surface perpendicular to the sheet surface.

  Subsequently, a polycarbonate sheet (first transparent protective layer 13) coated with a thermosetting adhesive (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE1825) is bonded to the surface of the obtained antiglare layer 10 and thermoset. Thus, the main body 1 was produced. The obtained main body 1 had a light transmittance of 78%.

  Next, a silicone rubber sheet (adhesive layer 14) coated with a thermosetting adhesive (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE-1800T) was bonded to the back surface of the antiglare layer 10 to cure the adhesive. .

  Next, printing is performed by an offset printing method using UV curable offset ink FD O New Series (trade name, manufactured by Toyo Ink Co., Ltd.) on one surface of the main body 1 (the surface of the first transparent protective layer 13 made of a polycarbonate sheet). After forming the image 2 into a predetermined shape, an optical filter was obtained by irradiating ultraviolet rays to cure the ink.

(Test example)
In the first embodiment, for each optical filter obtained by changing the dot diameter and the dot area ratio in offset printing as follows, the printed image of the optical filter overlaps with the portion where characters are displayed on the liquid crystal display screen. The visibility of the display image (characters) in the state was simulated.
Dot diameter: 0.15 mm, 0.2 mm, 0.3 mm
Halftone dot area ratio: 70%, 60%, 50%, 40%, 30%
In addition, as a liquid crystal display screen, the thing of the structure which is standard as a display screen of a mobile telephone and the size of one pixel is 300 micrometers, and the size of the character in a display image is 8 dots (8 pixels x 8 pixels). did.
The result is shown in FIG. Circles in the figure indicate halftone dots.

  As shown in the result of FIG. 3, even when a print image formed by halftone printing overlaps a display image (character), the display image can be visually recognized. In particular, in a range where the dot diameter in halftone printing is 0.2 mm or less and the halftone dot area ratio is 60% or less, the visibility of characters is improved.

1 is a perspective view showing a first embodiment of the present invention. It is sectional drawing which follows the II-II line | wire in FIG. It is a figure which shows the result of the test example concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical filter main body 2 Printed image 10 Anti-glare layer 11 Light transmission band 12 Light-shielding band

Claims (3)

An optical filter disposed on the viewing side of the image display screen,
In a region overlapping the display image on the image display screen, a print image formed by halftone printing is provided ,
Only the halftone dot of the printed image has a light transmittance of 50% or less in a wavelength range of 400 to 1200 nm,
An optical filter having a dot diameter of 0.2 mm or less and a dot area ratio of 60% or less in the halftone printing . The optical filter of claim 1, wherein the light transmission band and the light-shielding band is provided with an antiglare layer are disposed alternately. 3. The optical filter according to claim 1, wherein the outermost layer on the image display screen side is made of a rubber material having optical transparency, and the surface is mirror-finished.

Images